UPDATE 2-Third Israeli election looms as Netanyahu challenger fails to form gov't

Israel moved closer towards holding its third election in less than a year on Wednesday, after Prime Minister Benjamin Netanyahu's main challenger failed to form a government.

Benny Gantz's announcement that he would not meet a midnight deadline - following Netanyahu's own failure to do so - plunged the country even deeper into political deadlock at a time of spiralling security and economic concerns. For Netanyahu, not securing a fifth term as prime minister -or, alternatively, a rotating premiership with Gantz in a proposed unity coalition - may increase his vulnerability to possible indictment on corruption charges that he denies.

Gantz, a centrist former armed forces chief under Netanyahu, sought in a speech announcing his failed coalition talks to cast the conservative prime minister as responsible for the turmoil. "The people of Israel need a leadership of vision and not a leadership of immunity," Gantz said, alluding to efforts by Netanyahu's Likud party to pass laws that might protect him from prosecution.

With Wednesday's deadline due to expire within hours, a 21-day period will begin in which legislators can nominate any lawmaker, subject to the agreement of at least 61 of parliament's 120 members and a formal mandate from President Reuven Rivlin, to try to establish a coalition. Failure to do so automatically triggers an election in 90 days.